In recent years, an object detection device such as an ACC (Adaptive Cruise Control System) millimeter-wave radar unit that detects the presence or absence of an object in a traveling direction of a vehicle, a relative distance between vehicles, and the like has been mounted in the vehicle body front portion of vehicles such as automobiles. Such a radar unit is mounted on a vehicle rear side with respect to a front bumper, and a radar detection area of the radar unit radially extends from there toward a front side with respect to the vehicle body. Strict conditions are required for radio wave transmission in the detection area.
However, when the radar unit is mounted on the vehicle rear side with respect to the front bumper, the radar unit is often disposed near the front bumper in order to easily detect obstacles on the front side with respect to the front bumper and prevent the radar detection area from being too wide.
In this case, the radar unit is firmly fixed to the vehicle body in order to improve the object detection accuracy. However, the radar unit has a high rigidity. If such a component having a high rigidity is disposed right behind the front bumper, when a collision object such as a pedestrian collides against the vehicle body from the front side with respect to the vehicle, a large impact is applied to the pedestrian. Therefore, an attachment structure for protecting a pedestrian is known as disclosed in Japanese Patent Laid-open Publication No. JP 2007-30535A, for example. In Japanese Patent Laid-open Publication No. JP 2007-30535A, an attachment portion of a radar unit is caused to drop off upon collision from the front side to move back the radar unit toward the vehicle rear side, and thus the impact applied to the pedestrian is reduced.
However, in the conventional attachment structure disclosed in Japanese Patent Laid-open Publication No. JP 2007-30535A, there is a problem in that a large number of components for attaching the radar unit are required. Moreover, since the attachment structure disclosed in Japanese Patent Laid-open Publication No. JP 2007-30535A copes only with collisions from the front side with respect to a vehicle, there is the problem that the radar unit cannot move back upon collision from diagonally above, for example.
In view of the foregoing problems, it is an object of the present invention to provide a vehicle body front structure with which a radar unit can move back and an impact applied to a collision object can be reduced upon collision not only from the front side with respect to a vehicle but also from diagonally above.